In a communications network, such as an ATM network or the Internet, users should be charged for use of the network based on the amount of network resources utilized. The network resources that are consumed for each network connection include a number of processing cycles at various network processors, such as the routers or call processors of switching equipment or bandwidth usage on transmission facilities, as well as overhead services required to operate the networks, such as operations, maintenance and administration. Generally, costs associated with such overhead services are included in the total network capital, then pro-rated and amortized before being applied to individual users.
Typically, resource usage is measured in terms of the number of units of information that are sent and received by the user during a given connection and the duration of the connection. These measures provide an appropriate basis for charging a user since they represent the amount of processing performed by the network and the amount of bandwidth consumed by the network. Measuring resource usage by counting the number of units of information that is exchanged and possibly the connection time is an exact method but requires large processing power, especially for broadband networks having transmission rates in the range of several gigabits per second or higher.
In addition to the pricing of network usage, resource measurement also has important applications for short-term and long-term network planning, where the allocation and adjustment of network resources is of concern. Furthermore, resource measurements may also help develop accurate models for real-time control and management of networks, such as for quality of service control, call admission, resource usage management, distribution and control.
The bandwidth requirements of network applications vary significantly, from applications having relatively low requirements, such as telemetry and voice, to applications with much higher bandwidth requirements, such as video and large file transfers. Users of the World Wide Web (WWW), for example, access web servers for information. Such web server accesses result in one or more exchanges between web proxies and servers and the end user client machine until the original user request is satisfied.
Recent networking techniques advocate the “participation” of network routers and switches in applications, thus going beyond the traditional transmission of information units between end users and computers. For example, B. Li et al., “On the Optimal Placement of Web Proxies in the Internet,” Proc. of the 8th IFIP Conf. on High Performance Networking (HPN'98), Vienna, Austria (September 1998), suggests that processing and applications be included in Internet routers (or in servers and proxies co-located with routers) optimally distributed over the network. For applications that are frequently accessed by the end users, such as stock quotes and on-line auctions, D. Wetherall et al., “Introducing New Internet Services: Why and How,” IEEE Network Magazine (July/August 1998), suggests distributing such applications at the routers/servers (or at servers/proxies).
A number of statistical methods have been proposed or suggested for measuring the usage of a communications network. A technique for measuring the usage of a communications network based on equivalent bandwidth was proposed, for example, in C. Courcoubetis et al., “A Study of Simple Usage-Based Charging Schemes for Broadband Networks,” submitted August, 1998. While these measurement techniques may be adequate for current network applications, new methods for measuring the usage of a communications network are needed as the speed and diversity of applications increase and less is known about the effective bandwidth of new applications.
For example, applying the equivalent bandwidth measurement technique in an ATM network for real-time video conferencing between end users, accurately measures network resources as long as statistical characteristics of the video traffic is properly represented in the equivalent bandwidth model. The equivalent bandwidth measurement technique may not work, however, on the Internet, where a mix of text, audio and video clips are obtained from one or more web servers following a search and less is known about their statistical characteristics. The mix of such entities, and the bandwidth and processing that are required to deliver such entities to the end user, vary based on the application, the type of search (such as research, informational or entertainment), and the time of day when the search is performed. For example, searches performed during periods of time when the network is experiencing congestion may not last as long as searches performed when there is relatively little or no congestion. Thus, it is hard for users and service providers to predict the bandwidth and other resource needs ahead of a connection.